Fuzzy hybrid simulated annealing algorithms for topology design of switched local area networks

Topology design of switched local area networks (SLAN) is classified as an NP-hard problem since a number of objectives, such as monetary cost, network delay, hop count between communicating pairs, and reliability need to be simultaneously optimized under a set of constraints. This paper presents a multiobjective heuristic based on a simulated annealing (SA) algorithm for topology design of SLAN. Fuzzy logic has been incorporated in the SA algorithm to handle the imprecise multiobjective nature of the SLAN topology design problem, since the logic provides a suitable mathematical framework to address the multiobjective aspects of the problem. To enhance the performance of the proposed fuzzy simulated annealing (FSA) algorithm, two variants of FSA are also proposed. These variants incorporate characteristics of tabu search (TS) and simulated evolution (SimE) algorithms. The three proposed fuzzy heuristics are mutually compared with each other. Furthermore, two fuzzy operators, namely, ordered weighted average (OWA) and unified AND-OR (UAO) are also applied in certain steps of these algorithms. Results show that in general, the variant which embeds characteristics of SimE and TS into the fuzzy SA algorithm exhibits more intelligent search of the solution subspace and was able to find better solutions than the other two variants of the fuzzy SA. Also, the OWA and UAO operators exhibited relatively similar performance.